Aeration processes are utilized in the treatment of fluid for the purpose of mixing and increasing the dissolved oxygen (DO) content of the fluid. When used in a waste water treatment process, bacteria and other micro-organisms are supplied with oxygen to breakdown organic matter within the waste water in a purification process. In other applications, aeration processes are used in the treatment of water to meet the dissolved oxygen requirements for supporting fish and other aquatic organisms, in aquaculture, for example.
Known aeration apparatuses include surface aerators, diffuser/blowers, and rotor aerators. Surface aerators pump water upward and throw water into the air. Surface aeration systems require high horsepower and consume high amounts of energy in pumping water against the force of gravity. In blower/diffuser systems, forced air is introduced through diffusers at the bottom of a basin. Higher horsepower is required to pressurize atmospheric air to overcome the water head resistance. Oxygen rises vertically and escapes quickly before effective dispersion into water can take place. Rotor aerators consist of rotating aerators positioned at the surface of the water receiving treatment. Rotor systems have been known to be expensive to maintain and are high in energy consumption. They cast water into the air, creating an aerosol environment which releases offending odors into the air. Rotor systems are often used in cooling applications.
Another known type of aeration apparatus is an aspirator type aerator. These devices use an electrical motor driven rotating propeller disposed below the surface of the substance being treated. The propeller imparts a directed fluid flow over an air injection port, thereby producing an area of reduced pressure that draws in atmospheric air from an intake port through a draft tube and discharges it into the substance, e.g., the waster water being treated or the water containing marine life. Aspirator type aerators may be operated generally horizontally, creating a horizontal rather than vertical flow pattern within a treatment basin.
Known aspirator type aeration apparatus include Inhofer et al., U.S. Pat. No. 4,240,990 (Aeration Propeller and Apparatus); Durda et al., U.S. Pat. No. 4,280,911 (Method for Treating Water); Schiller, U.S. Pat. No. 4,741,825 (Mobile Vortex Shield); Schurz, U.S. Pat. No. 4,774,031 (Aerator); Durda, U.S. Pat. No. 4,806,251 (Oscillating Propeller Type Aerator Apparatus and Method); Fuchs et al., U.S. Pat. No. 4,844,816 (Method of Aeration at Specific Depth and Pressure Conditions); Rajendren, U.S. Pat. No. 4,844,843 (Waste Water Aerator having Rotating Compression Blades); Gross, U.S. Pat. No. 4,741,870 (Apparatus for Treatment of Liquids); and Durda, U.S. Pat. No. 4,954,295 (Propeller Aerator with Peripheral Injection of Fluid and Method of Using the Aerator).
The above known aerators require high speed propellers to create the vacuum for drawing in atmospheric air from an intake port and discharging it into the substance. Accordingly, these known aerators use high amounts of energy to create the vacuum.